Bug 1216133 – CVE-2015-2694 krb5: issues in OTP and PKINIT kdcpreauth modules leading to requires_preauth bypass

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Bug 1216133 - (CVE-2015-2694) CVE-2015-2694 krb5: issues in OTP and PKINIT kdcpreauth modules leading to requires_preauth bypass

Summary:	CVE-2015-2694 krb5: issues in OTP and PKINIT kdcpreauth modules leading to re...

Status:	CLOSED ERRATA

Aliases:	CVE-2015-2694

Product:	Security Response
Classification:	Other
Component:	vulnerability (Show other bugs)
Sub Component:
Version:	unspecified
Hardware:	All Linux

Priority	medium Severity medium
Target Milestone:	---
Target Release:	---
Assigned To:	Red Hat Product Security
QA Contact:
Docs Contact:

URL:
Whiteboard:	impact=moderate,public=20150427,repor...
Keywords:	Security

Depends On:	1216134 1218020
Blocks:	1210268 1216136
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Reported:	2015-04-28 10:46 EDT by Martin Prpič
Modified:	2016-06-13 08:03 EDT (History)
CC List:	8 users (show)

See Also:
Fixed In Version:
Doc Type:	Bug Fix
Doc Text:	A flaw was found in the OTP kdcpreauth module of MIT Kerberos. A remote attacker could use this flaw to bypass the requires_preauth flag on a client principal and obtain a ciphertext encrypted in the principal's long-term key. This ciphertext could be used to conduct an off-line dictionary attack against the user's password.
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Clone Of:
Environment:
Last Closed:	2015-11-20 00:43:50 EST
Type:	---
Regression:	---
Mount Type:	---
Documentation:	---
CRM:
Verified Versions:
Category:	---
oVirt Team:	---
RHEL 7.3 requirements from Atomic Host:
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External Trackers
Tracker	ID	Priority	Status	Summary	Last Updated
Red Hat Product Errata	RHSA-2015:2154	normal	SHIPPED_LIVE	Moderate: krb5 security, bug fix, and enhancement update	2015-11-19 03:16:22 EST

Groups: None (edit)

Description Martin Prpič 2015-04-28 10:46:49 EDT

The following flaw was found in MIT Kerberos:

In the OTP kdcpreauth module, the TKT_FLG_PRE_AUTH bit was set before the request was successfully verified. In the PKINIT kdcpreauth module, code 0 was returned on empty input or an unconfigured realm. Together, these bugs could cause the KDC preauth framework to erroneously treat a request as pre-authenticated.

In MIT krb5 1.12 and later, when the KDC is configured with PKINIT support, an unauthenticated remote attacker can bypass the requires_preauth flag on a client principal and obtain a ciphertext encrypted in the principal's long-term key. This ciphertext could be used to conduct an off-line dictionary attack against the user's password.

Upstream patch:

https://github.com/krb5/krb5/commit/e3b5a5e5267818c97750b266df50b6a3d4649604

Comment 1 Martin Prpič 2015-04-28 10:47:38 EDT

Created krb5 tracking bugs for this issue:

Affects: fedora-21 [bug 1216134]

Comment 3 Huzaifa S. Sidhpurwala 2015-05-03 23:38:29 EDT

Statement:

This issue does not affect the version of krb5 package as shipped with Red Hat Enterprise Linux 5 and 6.

Comment 5 Fedora Update System 2015-05-11 15:02:49 EDT

krb5-1.13.1-3.fc22 has been pushed to the Fedora 22 stable repository.  If problems still persist, please make note of it in this bug report.

Comment 6 Fedora Update System 2015-06-20 20:28:40 EDT

krb5-1.12.2-17.fc21 has been pushed to the Fedora 21 stable repository.  If problems still persist, please make note of it in this bug report.

Comment 7 errata-xmlrpc 2015-11-19 00:13:33 EST

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2015:2154 https://rhn.redhat.com/errata/RHSA-2015-2154.html

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